X.13

13. Nettle tea

"Wild phytotherapy" — high iron, chlorophyll-rich, prostate RCTs, and a spring cleansing tradition.

FODMAP: 🟢 lowEvidence: ★ ★ (human RCTs in BPH, traditional diuretic indication)Microbiota_position: quercetin + rutin + chlorophyll, a free-radical-scavenging flavonoid matrix

Nettle tea in 1 minute

What does it provide? A flavonoid matrix — quercetin and kaempferol (antioxidant, histamine-receptor modulating) —, chlorophyll, silica (silicon dioxide — connective-tissue and hair supporting), as well as non-heme iron (≈ 4.1 mg/100 g dried leaf) and outstanding vitamin K. The root's beta-sitosterol (phytosterol) inhibits the 5-alpha-reductase enzyme — Safarinejad 2005 RCT: 600 mg nettle root extract/day for 6 months significantly reduced BPH symptoms in 558 men.

How much? Hot tea: 1 tbsp (≈ 2 g) dried leaf / 250 ml water at 90–95 °C, covered, 8–10 min. 2–3 cups/day, with a 2-week break after 4–6 weeks. Cold macerate (for iron/silica maximization): 2 tbsp / 500 ml cold water for one night.

When to avoid? Pregnancy (emmenagogue, uterine-contracting effect — risk of miscarriage), lactation (data gap), warfarin treatment (high vitamin K destabilizes INR), lithium therapy (diuretic effect reduces clearance — toxic serum level), concurrently with diuretics (furosemide, hydrochlorothiazide — dehydration, electrolyte disturbance), severe kidney failure, uncontrolled T2D on glucose-lowering drugs (additive hypoglycemia).

📜 Historical Overview

Nettle is one of the most ancient medicinal plants of the Carpathian Basin. Galen, the ancient Greek physician, already recommended nettle compresses for joint pain. In Hungarian folk medicine, Péter Melius Juhász's "Herbarium" (1578) describes it in detail: "The Nettle, which some call Urtica..." for iron deficiency, joint complaints, as a diuretic. Spring nettle soup was a key element of the Lenten diet in Catholic tradition. From the mid-20th century, phytopharmacology began its scientific investigation; from the 1990s, standardized Urtica extracts appeared with BPH indication.

Scientific Background

Active-substance profile

  • Iron — 4.1 mg/100 g dried leaf (non-heme form)
  • Chlorophyll — high, "green blood" composition
  • Quercetin, kaempferol — flavonoids
  • Carotenoids — vitamin A precursors
  • Silica (silicon dioxide) — connective-tissue supporting
  • Beta-sitosterol (mainly in the root) — BPH effect
  • Histamine, serotonin — in the fresh leaf (responsible for the sting, inactivated by cooking)

Clinical studies

Safarinejad 2005 randomized, double-blind, placebo-controlled study in 558 BPH men: 6 months of 600 mg nettle root extract/day significantly reduced IPSS (International Prostate Symptom Score) and improved maximum urinary flow (Journal of Herbal Pharmacotherapy 5(4):1-11)[1864].

Lopatkin et al. 2005 German multicenter randomized study in 257 BPH patients: a nettle + saw palmetto combination significantly improved symptoms, with a strong effect vs. placebo (World Journal of Urology 23(2):139-146)[1865].

Roschek et al. 2009 in an allergic rhinitis study, demonstrated the histamine-receptor antagonism of nettle extract in vitro (Phytotherapy Research 23(7):920-926)[1866].

Mechanism

  • BPH: beta-sitosterol inhibits testosterone-to-DHT conversion (5-alpha-reductase); 17β-HSD inhibition; reduction of SHBG-binding affinity.
  • Diuretic: Na+/K+ pump modulation in the kidney.
  • Anti-inflammatory: NF-κB pathway and TNF-α inhibition[1867].
  • Iron source: although it contains iron, it is not sufficient on its own for clinical-level iron-deficiency replacement.
✅ Combine with
  • Lemon juice — vitamin C increases iron absorption (from non-heme iron).
  • Fresh chopped leaf into soup — Hungarian spring diet.
  • Dandelion leaf — synergistic diuretic.
  • Honey — folk tradition, flavoring.
🚫 Avoid combining with
  • Diuretics (furosemide, hydrochlorothiazide) — additive effect, risk of dehydration and electrolyte disturbance.
  • Lithium — diuretic effect may reduce lithium clearance, toxic serum level.
  • Anticoagulant (warfarin) — high vitamin K content (nettle is richer in vitamin K than spinach!) → risk of INR drop.
  • Glucose-lowering drugs — synergistic effect → risk of hypoglycemia.
⚠️ When to avoid — condition-specific
  • Pregnancy — emmenagogue (uterine-contracting) effect; potentially can induce miscarriage.
  • Lactation — data are limited.
  • Severe kidney failure — although it supports excretion, in severe cases it burdens the kidney.
  • Warfarin treatment — vitamin K destabilizes INR.
❌ Myths and their refutation
- "Nettle replenishes iron deficiency." — PARTIALLY true; it contains iron, but the non-heme form has low biological availability; in clinical iron deficiency, supplementation is necessary. - "Anyone can drink it without limit." — A strong diuretic and vitamin K source → drug interactions. - "Nettle loses its effect when cooked." — INCORRECT; cooking only inactivates the histamine and serotonin that cause the sting; flavonoids and chlorophyll are stable.
🍳 Kitchen Protocol

Steeping (hot tea)

  1. Leaf-to-water ratio: 1 tbsp (≈ 2 g) dried nettle leaf / 250 ml water.
  2. Water temperature: 90–95 °C.
  3. Steeping time: 8–10 min covered (preserves chlorophyll and volatiles).
  4. Serving: max. 2–3 cups daily; with a 2-week break after 4–6 weeks.

Cold macerate (maximizing iron source)

  1. 2 tbsp dried nettle / 500 ml cold water.
  2. One night at room temperature, steeping.
  3. In the morning, strain, add lemon juice, drink freshly sip by sip.
  4. Cold extraction retains more minerals and silica.

Fresh nettle soup (Hungarian folk recipe)

  1. Young spring nettle shoots (pick with gloves!).
  2. 2 min scalding removes the sting.
  3. Onion, potato, nettle; sour cream, lemon juice.
  4. A complete "spring cleansing" meal on its own.

Storage

In a dark, airtight container; 1-year stability. The vivid green color is a sign of freshness; brownish-gray → already degraded.

References

[1864] Safarinejad MR (2005). Urtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomized, double-blind, placebo-controlled, crossover study, 5(4):1-11. Journal of Herbal Pharmacotherapy. 2005. Link

PURPOSE: To determine the effects of therapy with Urtica dioica for symptomatic relief of lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). MATERIAL AND METHODS: A 6-month, double-blind, placebo-controlled, randomized, partial crossover, comparative trial of Urtica dioica with placebo in 620 patients was conducted. Patients were evaluated using the International Prostate Symptom Score (IPSS), the maximum urinary flow rate (Qmax), postvoid residual urine volume (PVR), Serum Prostatic- Specific Antigen (PSA), testosterone levels, and prostate size. At the end of 6-month trial, unblinding revealed that patients who initially received the placebo were switched to Urtica dioica. Both groups continued the medication up to 18 months. RESULTS: 558 patients (90\%) completed the study (287/305, 91\% in the Urtica dioica group, and 271/315, 86\% in the placebo group).

[1865] Lopatkin N, Sivkov A, Walther C, et al. (2005). Long-term efficacy and safety of a combination of sabal and urtica extract for lower urinary tract symptoms — a placebo-controlled, double-blind, multicenter trial, 23(2):139-146. World Journal of Urology. 2005. Link

The efficacy and tolerability of a fixed combination of 160 mg sabal fruit extract WS 1473 and 120 mg urtica root extract WS 1031 per capsule (PRO 160/120) was investigated in elderly, male patients suffering from lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia in a prospective multicenter trial. A total of 257 patients (129 and 128, respectively) were randomized to treatment with PRO 160/120 or placebo (127 and 126 were evaluable for efficacy). Following a single-blind placebo run-in phase of 2 weeks, the patients received 2 x 1 capsule/day of the study medication under double-blind conditions over a period of 24 weeks. Double-blind treatment was followed by an open control period of 24 weeks during which all patients were administered PRO 160/120. Outcome measures for treatment efficacy included the assessment of the patients' LUTS by means of the I-PSS self-rating questionnaire and a quality of life index as well as uroflow and sonographic parameters. Using the International Prostate Symptom Score (I-PSS), patients treated with PRO 160/120 exhibited a substantially higher total score reduction after 24 weeks of double-blind treatment than patients of the placebo group (6 points vs 4 points; P=0.003, one tailed) with a tendency in the same direction after 16 weeks.

[1866] Roschek B Jr, Fink RC, McMichael M, Alberte RS (2009). Nettle extract (Urtica dioica) affects key receptors and enzymes associated with allergic rhinitis, 23(7):920-926. Phytotherapy Research. 2009. Link

A nettle (Urtica dioica) extract shows in vitro inhibition of several key inflammatory events that cause the symptoms of seasonal allergies. These include the antagonist and negative agonist activity against the Histamine-1 (H(1)) receptor and the inhibition of mast cell tryptase preventing degranulation and release of a host of pro-inflammatory mediators that cause the symptoms of hay fevers. The nettle extract also inhibits prostaglandin formation through inhibition of Cyclooxygenase-1 (COX-1), Cyclooxygenase-2 (COX-2), and Hematopoietic Prostaglandin D(2) synthase (HPGDS), central enzymes in pro-inflammatory pathways. The IC(50) value for histamine receptor antagonist activity was 251 (+/-13) microg mL(-1) and for the histamine receptor negative agonist activity was 193 (+/-71) microg mL(-1). The IC(50) values for inhibition of mast cell tryptase was 172 (+/-28) microg mL(-1), for COX-1 was 160 (+/-47) microg mL(-1), for COX-2 was 275 (+/-9) microg mL(-1), and for HPGDS was 295 (+/-51) microg mL(-1). Through the use of DART TOF-MS, which yields exact masses and relative abundances of compounds present in complex mixtures, bioactives have been identified in nettle that contribute to the inhibition of pro-inflammatory pathways related to allergic rhinitis.

[1867] Chrubasik JE, Roufogalis BD, Wagner H, Chrubasik SA (2007). A comprehensive review on the stinging nettle effect and efficacy profiles, 14(7-8):568-579. Phytomedicine. 2007. Link

Nettle root is recommended for complaints associated with benign prostatic hyperplasia (BPH). We therefore conducted a comprehensive review of the literature to summarise the pharmacological and clinical effects of this plant material. Only a few components of the active principle have been identified and the mechanism of action is still unclear. It seems likely that sex hormone binding globulin (SHBG), aromatase, epidermal growth factor and prostate steroid membrane receptors are involved in the anti-prostatic effect, but less likely that 5alpha-reductase or androgen receptors are involved. Extract and a polysaccharide fraction were shown to exert anti-inflammatory activity. A proprietary methanolic nettle root extract and particular fractions inhibited cell proliferation.

PG
Food Handbook · Authors: Dr. Patay Gábor — physician, microbiota specialist · Dr. Bezzegh Attila — medical director, clinical microbiologist · Dra. Anna Munar — physician, exposome specialist
MicroBiome Bank — medically reviewed professional content. Last updated: 2026.